Friday Rock Blogging: Gnammas
Gnamma is derived from a Western Australian aboriginal* term for a hole in rock, particularly one which is full of water. The one shown here is from Yosemite again, but unlike so many other features in that park, this gnamma wasn’t formed by glaciers. Instead, it is a testament to the awesome power of small puddles, which speed up the process of erosion in what is initially a slight depression.
Use of the term seems, from quick Google inspection, to be largely restricted to Australia – which is a pity as I think it’s a fun word. The author of the USGS report from which the photo was taken calls it a “weather pit” but that term hasn’t caught on (the report was published in 1913). I’m not aware of any specific terms for these sorts of holes in common use in the American geological community, other than “pothole” which is quite generic, but of course this isn’t my area of expertise so perhaps some gentle reader can set me straight on this point.
*The internet isn’t telling which language specifically, sorry.